Distillation of tar



Nov. 6, 1934. G. E. MccLosKEY DISTILLATION 0F TAR 4 sheets-sheet 1 FiledJune 3. 1950A INVENTOR EMM ATTORNEYS N0V 6, 1934- G. E. MccLosKEYDISTILLATION OF TAR Filed Jme 3. 195o 4 Sheets-Sheet 2 MSW k ATTORN EYSNov. 6, 1934. G. E. MccLosKEY 1,979,838

V DISTILLATION OF TARl l Filed June 3. 1930 4 Sheets-Sheet 3 QR ww Nov.6, 1934- G. E. MccLosKx-:Y

DISTILLATION OF TAR Filed June 3. 1930 4 Sheets-Sheet 4 g/ INVENT fan!BW ATTORNEY Patented Nov. 6, 1934 UNITED STATES PATENT oFFlcEDIsTmLATToN oF TAR Application June 3, 1930, Serial No. 459,025 2oclaims. (c1. 2oz-'30)l 'I'his invention relates to an improved processof distilling tar with combustion gases.

The present invention provides an improved method of distilling coal tarwith combustion 5 gases in which the gases employed have a radicallyhigher temperature than that heretofore proposed forv suchdistillationand in which the gases are sprayed with the tar in the formof an intense spray and in an amount such that the gases are almostinstantly cooled and coking of the tar by the hot gases is thus avoided.Distillation is effected and pitch of high melting point is producedwith only minimum decomposition of the tar.

The combustion gases, according to this -mvention, are employed at atemperature above that at which complete distillation and carbonizationof the pitch residue resulting from the distillation of coal tar wouldtake place, and these gases are employed in such a manner thatobjectionable carbonization is avoided e and rapid and eectivedistillation is accomplished.

In the present process I employ combustion gases at a high temperature,e. g. around 500- l000 C. Coal tar if heated in the usual manner to sucha high temperature would rapidly carbonize. In the process of thepresent invention tar is distilled without objectionable carbonizationand the combustion gases are employed at a high temperature in laparticularly advantageous manner.

The combustion gases employed for the tar distillation of this inventionmay be fresh hot combustion gases, i. e. gases resulting directly fromthe combustion of carbonaceous materialy or preferably the fresh hotcombustion gases are partially cooled before they are employed for thetar distillation.

Fresh hot combustion gases which are too hot for distilling tar even bythe method of this invention, may be'cooled in. any suitable manner andmay then be used for distillation. 'I'hey may be cooled, for example, bybringing a gas or a liquid into indirect heat interchanging relationwith them to cool them before they are brought into direct contact withthe tar. The tar to be distilled may be preheated by being brought intosuch indirect heat interchanging relation with the hot gases in a pipecoil still before being brought into direct contact with the indirectcontact with these fresh hot combustion gases. The hot combustion gasesmay be cooled by indirect contact with air or they may be allowed tocool merely thru radiation of heat from the walls of the conduit thruwhich they pass from` the burner or burners to the still.

Fresh hot combustion gases may be cooled by diluting them with a gas oflower temperature. Ordinary stack gases, such as the waste ue gases froma coke oven battery, may be blended with the hot gases and the heat inthe waste gases may thus be utilized. The fresh gases may bediluted-with steam, which may advantageously be wet steam; when such agas mixture is cooled to C., for example, to effect the condensation 70of oils, the relative amount of non-condensable gas present is less andthe loss of oils such as light oil in the gases is correspondinglyreduced. Somewhat the same effect may be accomplished by sprayingthefresh hot combustion gases with 75 a limited amount of water. Theproportion of diluent employed or the extent to which the gases arecooled by other means should be so regulated that the resulting gasesare at the high temperature desired for the tar distillation.

Fuel gas, such as coke oven gases after they have been passed thru aby-product recovery condensing system, may be employed for diluting thefresh combustion gases. Such gases are desirable as a diluent because oftheir low oxygen content. The oxygen content of the gases brought intodirect contact with thetar should preferably be kept low. Where thediluent contains oxygen thev combustion of the fuel must be so regulatedas to produce combustion gases of unusually low oxygen content. Where adiluent is employed and it contains no oxygen or only a small percent ofoxygen, the amount of oxygen in the combustion gases may be somewhathigher. 'I'he oxygen content of the gases brought into c ontact with thetar should not be more than a few percent, i. e. considerably less than5%. Fuel gases are a desirable diluent because they can be employedtodecrease the oxygen content of the combustion gases. A furtherdesirable feature of such fuel gases as, for example, coke oven gases,is that they are already saturated with condensable oil constituents ofthe same character as those resulting from the distillation of tar andtherefore no condensable vapors are lost in the fuel gases escaping fromthe condensers of the tar distillation unit.

When fuel gases such as coke oven gases or other coal carbonizationgases are employed as the diluent, the gases escaping from the congasesresulting ,from the combustion may be cooled by diluting with fuelgases. These fuel gases may be introduced into and blended with thefresh combustion gases by being passed thru the burners in excess ofthat required for the combustion. Instead of thus being blended with thecombustion gases, additional fuel gases may be blended with thecombustion gases in any suitable manner between the burners and the tarstill.

Any suitable fuel may be employed for producing the combustion gasesemployed for the distillation.

According to the present invention, fresh hot combustion gases orcombustion gases which have been brought to the temperature desired forthe tar distillation are brought into a chamber containing a body of thetar or pitch to be distilled. The gases'enter the chamber at a hightemperature, for example a temperatureof 500-1000 C. The tar in thechamber is atomized or sprayed up into the gases with such intensity ofspray that the tar is rapidly distilled and the, gases are almostinstantly cooled from their high tempera' ture to a temperatureapproaching that of the pitch formed by the rapid distillation of thetar.

Such intense spraying oratomizing of the tar or pitch can readily beaccomplished by means of one or more rapidlyrotating rolls either smoothor with peripheral grooves or the like, which dip into the body of taror pitch in the bottom of the apparatus and cause a continuous intensespray of the tar or pitch to ll all parts of the apparatus so that theentering high temperature gases are rapidly cooled and almostimmediately brought into equilibrium with the intense spray withresulting cooling of the gases and rapid heating and vaporization of oilconstituents from the spray.

Thus high temperature combustion gases and tar can be supplied inregulated amount to a still having one or more rapidly rotating sprayrolls and the rate of supply of the gases and of the tar can be soregulated that rapid and continuous distillation can be accomplished andpitch of high melting point produced, for example pitch up to around 400F. melting point or higher, with an unusually high yield of oil from thetar amounting to around '75% or higher and varying somewhat with thecharacter of the tar distilled. The rapidity with which the hot gasesare cooled to a temperature below that at which objectionabledecomposition of the pitch takes place is such that the decompositioncan be reduced to a minimum and rapid and effective distillation benevertheless accomplished.

Where some decomposition is desired, for example in order to increasethe carbon content of the pitch residue, this vcan readily be accomplished by regulation of the temperature of the gases entering thestill,- the rate of supply of the "gases and the tar to the still orprolongation of the time of contact of the pitch and 4gases within thechamber. f. l l mtg In carrying out the process the large surface ofcontact between the tar and gases will ordinarily be such that the gasespass thru the chamber at a rapid rate and escape so that they are inconytact with the intense spray of tar or pitch only for a short periodof time, amounting, for example, to from one to ve seconds more or less,depending upon the size of the apparatus and the conditions ofoperation. Similarly the supply of tar or partly distilled tar to thestill and the removal of high melting point pitch therefrom can be soregulated that the entire period of operation from the time the tarenters until the pitch leaves will be short, amounting, for example, toas little as one minute or less in some cases, or to five or ten minutesor more in other cases.

'Only a very short time is required with the intense atomizing orspraying of the tar or pitch into the hot gas and with a regulatedsupply of the hot gas to accomplish distillation of the tar to thedesired extent.

The tar which is distilled may be ordinary coal tar from coke oven 'orgas retort plants or it may.

be other tar such as low temperature tar, water gas tar, producer gastar, etc. Instead of distilling total tar heavier or lighter tarfractions can be distilled, such as the heavier tar recovered from thecollector main of a by-product recovery plant or the lighter tarrecovered from the condensers of such a plant.

The distillation can be carried to the extent necessary to produce apitch of higher or lower melting point as desired and a greater or lesspercentage of distillate oils, but it is one advantage of the presentprocess that it enables an unusually high yield of distillate oils to bepro- A duced and an unusually high melting point pitch to be producedrapidly and continuously and with relatively little decompositionof thepitch produced. In some cases a pitch of intermediate melting point maybe desired, for example around or 200 or 250 F. melting point, while in.other cases higher melting point pitches may be desired up to 300 F.melting point or even up to 400 F. melting point or higher. 'Ihesepitches can readily be produced according to the present process. 1

The still itself lmay vary in its construction but it should haveprovision for forming an intense.

spray of the tar or pitch to be distilled so that the hot gases will bealmost instantly cooled to a temperature below that at whichobjectionable carbonization and coking will result. The forming of suchan intense spray with a rapidly rotating roll will not only eiect rapidcooling of the gases and utilization of their heat for distillation, butwill keep the interior of the still washed with the tar and pitch sprayand thereby prevent the interior walls from becoming coated with coke.The tar is advantageously supplied to the. still in a continuous mannerand the pitch produced continuously withdrawn.

In distilling tar to produce a pitch of high melting point, for examplearound 400 F. 'or higher, the gases and admixed oil vapors resultingfrom the distillation will leave the still at a high temperature, forexample around 300 C. or 325 C. or higher, although the temperature maybe somewhat lower and may vary with the method of operation, thecharacter or melting point of pitch produced, the temperature and amountof gasesentering the still, etc. Gases and oil vapors at suchtemperatures carry a large amount for preheating and distilling tar andsuchpreheating and distillation can be combined with the distillationproper so that the partly distilled tar resulting from such preheatingand distillation is supplied to the still proper for furtherdistillation. Such preheatingl of the tar'by the hot gases and vaporswill result in simultaneously cooling of of heat which canadvantageously be employed direct contact with the hot gases.

the gases and vapors and condensation of some of the higher boiling oilconstituents therefrom. By carrying out the condensation in acountercurrent manner, a part of the heat contained in the gases andvapors can be recovered for use in preheating and then distilling tar atthe same time that the oil vapors are thus condensed.

Tar preheated by indirect contact with the gases and vapors coming fromtne still may be discharged into a vapor box to effect partialdistillation ofthe tar and removal of low boiling constituents from thetar before it is brought into 'Ihis is advantageous since it allowsvrecovery of the vapors of the low boiling oils distilled from the tar inthis manner without dilution with hot gases and :by thus rst removingthe low boiling constituents before bringingthe tar into direct contactwith the hot combustion gases loss of such low boiling constituents invapor form by dilution with the combustion gases may be prevented.

A portion of the gases coming from the condensers may be recirculatedwhere desired and be employed for cooling and diluting fresh hotcombustion gases before they enter the tar still. The gases may bepassed thru the burner and be used for atomizing the fuel where fueloil, for example, is employed, or the gases may be blended with thefresh combustion gases after they have left the combustion chamber.

Tar may be preheated by passing it thru a pipe `coil still in heatinterchanging relation with the fresh hot combustion gases when it isdesirable to lower the temperature of the gases before they enter intodirect contact with the tar, and the tar thus heated may be passed intoa vapor box to eiect the vaporization of low boiling oils therefrom andthe residue comprising only higher boiling oils may then be brought intodirect contact with the hot combustion gases. This affords anothermethod of removing low boiling constituents from the tar before it isbrought into direct contact-with the hot gases.

Where the tar is heated and then flashed before being brought intodirect contact with the hot gases, the vapor box in which the tar isashed may be maintained under a vacuum, where desirable, to assist inthe removal of the lower boiling oils.

It is one advantage of the present invention that the use of the hightemperature gases enables a radically smaller amount of gases to beemployed for accomplishing the distillation than would be necessarywhere low temperature gases were employed so that the oil vaporsdistilled are admixed with a relatively small amount of gases. As aresult the oil vapors can more readily be condensed from the gases.Further, if the hot gases and vapors leaving the still are employed forpreheating and partially distilling the tar, an ncreased rate ofdistillation can be realized with the same amount of gases.

In the specification and claims the word tar Vis used to include rawtar, dehydrated tar, heavier and lighter tar fractions, and partiallydistilled tar, such as semi-pitch.

The invention will be further described in connection with theaccompanying drawings, which illustrate in a somewhat conventional anddiagrammatic manner an arrangement of apparatus for carrying out theinvention, but it is intendedA and will be understood that the inventionis not limited thereto.

Fig. 1 is an elevation of apparatus adapted for carrying out theinvention;

Fig. 2 is a section on the line 2-2 of Fig. 1;

Fig. 3 is an elevation of a modied form of apparatus;

Fig. 4 is a plan view of another modification in which the tardistillation is carried on in conjunction with the operation of a coaldistillation plant; and

Fig. 5 is an elevation of a part of the apparatus shown in Fig. 4.

Fig. 1 shows apparatus in which the fresh hot combustion gases from thecombustion chamber l pass into the still 2 where they are brought intocontact with tar or semi-pitch and are employed for distillation of thistar or semi-pitch by direct contact therewith. The gases and vaporsresulting from this distillation pass up thru the saturating tower 3 andthence to the heat interchanger 4. In the heat interchanger they areemployed for preheating the tar which enters thru the line 5. From theheat interchanger 4 the gases and remaining vaporsfpass to the condenser6. This is here shown as a direct contact condenser in which the gasesare sprayed with water thru the sprays 7. 'I'he water and condensatedrawn olf from the bottom of the condenser are separated in the decanter8 and water and a medium-boiling oil fraction are separately collectedin the tanks 9 and 10. Higher 'boiling oils are drawn off from thebottom of the heat interchanger into the tank 1l.

The tar is heated in the heat interchanger above the distilling point oflower boiling constituents in the tar and the heated tar is passed intothe vapor box 15. Low boiling constituents which are vaporized in thevapor box are condensed in the condenser 16 and collected in the tank17. This fraction may be rich in naphthalene and commercially valuabletar acids.

The residue from this dashing operation is pumped thru the line 18 bythe pump 19 and sprayed into the saturating tower thru the spray 20. Tarpasses over the baliles 21 and is further distilled by the hot gases andvapors which leave vthe still thru the -pipe 22. The residue which is apitch or semi-pitch, enters the still 2 thru the line 23.

The semi-pitch and the hot combustion gases from the combustion chamberpass thru the still in a concurrent direction. 'I'he semi-pitch issprayed and resprayed into contact with the hot gases as they enter thestill and the pitch produced by further distillation of this semi-pitchis brought into contact only with gases which have' been partiallycooled and are partially saturated as a result of the distillation ofthe semi-pitch therein. Such concurrent flow of the hot gases andmaterial to be distilled together with intense spraying of thel tarproduced by rapid rotation of the roll 25 prevents undesirabledecomposition of the pitch even though the gases enter the still at atemperature high enough to otherwise effect substantial decomposition.When desired, as when gases of relatively lower temperature areintroduced into still 2, the tar or pitch may be introduced into thestill thru the gas outlet pipe 22, and the overflow 28 and trap 27 maybe at the gas inlet end of the still; in such an apparatus gas and taror pitch now in countercurrent directions.

The roll 25 which is located in the still may be sixteen inches indiameter. It is rapidly rotated by the motor 26 at `a speed of 900-1500R. P. M. The roll dips to but a slight extent into the body of tar orpitch in the still and produces a fine intense spray of thetar which llsthe entire distilling chamber and flushes its walls. This intense sprayof tar rapidly cools the gases and the tar is rapidly distilled. In thismanner pitch of high melting point may be produced.

The pitch is drawn off from the chamber in any suitable manner. It maybe drawn off thru a trap 27 by means of the levelling arm 28. The angleat which this levelling arm is maintained determines the depth to whichthe roll 25 dips into the body of tar or pitch. Where high melting pointpitch is to be produced it may advantageously be drawn off into a trough29 and be chilled and granulated therein by a spray of water from theline 30. The resulting pitch product is then collected in the bin 31.

The gases and vapors leave the still thru the pipe 22 `and pass up overthbatlie 21 where entrained particles of the spray are removed trom thegases. Bailles 32 are provided to remove any particles of spray whichmay be carried up thru the saturating tower by the hot gases and vaporsyfrom the spray nozzle 20. The gases leaving the saturating tower or thecondensers are substantially clean gases and yield clean oils. Particlesof smoke or carbon, etc., which may be present in the gases as theyleave the combustion chamber are removed from the gases by the scrubbingaction of the intense tar and pitch spray maintained in the still, andreduced to an amount that insures the production of commercially cleanoils.

A ne wire gauze may, if desired, be provided at 33 to prevent explosionsand other safety means such as means for regulating the oxygen contentof the gases may be employed to prevent ignition of the gases and vaporsin the tar still from the combustion chamber.

Gas, tar, pitch, oil, coal, coke or other fuel may be burned in thecombustion chamber. Firebrick or other heat-resistant material isadvantageously placed within the combustion chamber in the way wellknown in the art to expose a large surface of highly heated refractorymaterial to aid in effecting complete combustion.

According to the arrangement shown in Fig. 3, the fresh hot combustiongases pass over the pipe coil 40 and are partially cooled before theyenter the still 41 by indirect heat interchange with tar which passesthru the coil. Distillation is effected in the still by direct contactbetween tar or semi-pitch and the hot gases, and the resulting gases andvapors pass from the still thru the settling chamber 42 where bafllesare provided to effect removal of any spray from the gases and vapors'.From the settling chamber they pass-to the condenser 43. The still 41 isprovided with a spray roll 44 and the operation of this still is similarto the operation of the still 2 of Fig. 1 which is equipped with thespray roll 25. The pitch produced is collected in the bin 45.

The condenser 43 may be a direct or indirect condenser. It is shown asan indirect condenser in the drawings in which water enters at 46 andpasses out through the exit line 47. The oil recovered in the condenser43 is collected in the tank 48.

The cooled gases which leave the condenser 43 are in part recirculatedby the blower 49 thru the line 50 and mixed with the hot gases from thecombustion chamber before they enter the still 4l. Baiiles or suitablemeans may be provided for effecting admixture of these recirculatedgases with the fresh gases from the combustion chamber, Where necessary.

The tar is heated in the coil 40 above the 52 where they are condensed.They are collected boiling point of lower boiling constituents. Theheated tar is passed to the vapor box 51 where lower boilingconstituents are volatilized. Vapors from the vapor box are passed intothe condenser in the tank 53 and constitute a low boiling oil. Theresidue from the flashing` operation in the vapor box is conveyed to thestill 41. This residue is distilled by direct contact with thecombustion gases and converted to pitch within the still.

Lower boiling oils are flashed from the tar in the vapor box and thegases which leave the condenser 43 are therefore substantially free ofvapors of such lower boiling oils. A regulating valve 54 is provided tocontrol the amount of gases recirculated through the still 4l. Theposition of this valve may advantageously be controlled by automatictemperature control means so that gas at uniform temperature is suppliedto the still `4l. The balance of the gases not recirculated thru theline 50 are exhausted to the atmosphere thru the pipe 55.

Figs. 4 and 5 illustrate how distillation with combustion gases may becarried out in conjunction with the operation of a coke oven battery.The coke oven battery is indicated at 60. The individual ovens of thebattery are connected in the usual way with a gas collector main 61. Thegases pass from the collector main thru the crossover main 62 tocondensers 63 which may be direct 105 or indirect condensers.` They arehere/shown as direct condensers. The tarry oil which separates from thegases in these condensers is collected in one or more decanters 64. Theammonia liquor' and tarry oils are separately collected in the 110 tanks65 and 66. Tar and ammonia liquor from the collector main 61 arecollected in the decanter 67. From this decanter the tar and ammonialiquor may be separately collected in the tanks 68 and 69.

From the condensers 63i4-ti1e gases pass thru an exhauster "10 to meansfor the recovery of ammonia and light oil. Apparatus for the recovery ofammonia is indicated in a diagrammatic way as an ammonia saturator '71.From the ammonia 120 saturator the gases pass to a light oil absorber72. From the light oil absorber the gases pass to storage or fuel gasmains or t6 `means for the removal of sulfur, etc. This apparatus mayall be of the usual type.

The tar still shown at 80 is similar to the still described inconnection'with the preceding iigures. It is equipped with a spray roll81. Combustion gases pass from the combustion chamber 82 into the stillwhere they are sprayed with a ne intense spray of tar and pitch. The taris distilled to pitch and the gases and vapors pass from the still tothe saturating tower 83. This is similar in construction and operationto the saturating tower 3 of Fig. 1. From this saturating tower thegases pass to the heat interchanger 84 and then to a direct condenser 85where they are cooled progressively for the separation of heavy oilwhich is 'collected in the tank 86, and lighter oil which is drawn oiinto the decanter 87 and 140 thence to the storage tank 88. An exhauster89 is provided for drawing the gases and vapors thru the system.'

The tar enters the heat interchanger thru the pipe 90 and is heatedtherein simultaneously with 145 the condensation of the'heavy oil. It issprayed into contact with the gases and vapors in the saturating tower83 where lower boiling oils are distilled from the tar. 'Ihe partiallydistilled tar or semi-pitch which results from this distillation 150 isconveyed thru the line 91 to the still and it enters the still in directcontact with the high temperature combustion gases admitted thereto andis rapidly heated and distilled by being sprayed into the gases in theform of a ne intense spray by the spray roll 81.

. Fuel gas from the coke oven battery is burned in the combustionchamber 82 to provide heat for the distillation in the still 80. Thefuel gas is supplied to the burner 92 thru the line 93 by the blower 94from beyond the benzol extractor 72. A valve 95, preferably an automaticpressure regulating valve, is provided to regulate the amount of gasthus supplied to the burner 92. When desirable, the hot combustion gasesresulting from such combustion may be diluted by blending with fuelgases taken from the byproduct recovery system. The drawings show a pipe96 equipped with thermostatically regulated valve 98 for this purpose.Fuel gas may be supplied thru this line 96 for diluting the freshcombustion gases and lowering their temperature. An excess of fuel gasmay be supplied to the burner thru the line 93 for this purpose. Careshould be taken to prevent deposition of carbon from the fuel gases whenexcess fuel is supplied to the burner in this manner.

The gases leaving the system have a substantial fuel value. They may beblended Vwith the fuel gases employed for heating the coke ovens or maybe employed otherwise as fuel gases.

The apparatus shown provides for the collection of various oil fractionsin addition to a high melting point pitch. The melting po'int of thepitch may be controlled by regulatingthetemperature and amount of gasesand the rate and temperature of the tar fed to the still. Other oilfractions may be recovered as ldesired by providing suitable condensingmeans.

In the apparatus illustrated the general ow of the tar and pitch and hotgases in the still is a concurrent flow so that the hot gases enteringthe still come in contact with the tar containing the largest proportionof oil constituents. The rapid distillation of such oil constituentsrapidly cools the gases to a temperature below that at whichobjectionable decomposition of the pitch will take place. The pitchproduced will escape from the outlet end of the still approximately inequilibrium with the escaping gas and vapors. Even with gases atsomewhat lower temperatures than those mentioned, combustion gases canbe utilized in a particularly advantageous manner in a still of the typeherein described.

I claim:

1. The method of distilling tar and producing distillate oils and pitchtherefrom, which comprises bringing tar into direct contact withcombustion gases at a temperature above that at which coking of tar orpitch normally occurs in the form of a spray of such intensity that thetar is rapidly distilled to pitch and the gases are almost instantlycooled to a temperature below that at which objectionable coking of thetar or pitch takes place and withdrawing the resulting gases `and oilvapors and cooling-them to condense oils therefrom.

2. The method of distilling tar and producing distillate oils and pitchtherefrom, which comprises bringing combuston gases at a temperature inexcess of 500 C. in the form of a continuous stream into a stillcontaining a body of tar tobe distilled, spraying the tar and pitchresulting from the distillation of .said tar into the gases in.

the form of a spray of such intensity that the gasesk are almostinstantly cooled to a temperature approximating that of the spray andthe spray is heated to a temperature approximating that to which thegases are cooled thereby rapidly distilling the tar and producing pitch,withdrawbringing the tar into contact with the hot combustion gases inthe form of a spray of such intensity and in such an amount that thegases are almost instantaneously cooled to a temperature at which cokingis avoided.

4. The method of distilling tar and producing distillate oils and pitchtherefrom, which comprises burning a carbonaceous fuel and cooling theresulting combustion gases to a temperature not below 500 C., passingthe gases at this high temperature into a still, spraying tar into thegases in the form of a fine intense spray which rapidly cools the gasesand distills the tar to pitch, continuously adding tar to the still andwithdrawing pitch therefrom and cooling the gases and vapors resultingfrom the distillation to condense oils therefrom.

5. The method of distilling tar and producing pitch of a melting pointof at least 350 F., and

obtaining a high yield of distillate oils, which comprises passing hotcombustion gases into one end of a still containing a body of tar andpitch, continuously supplying tar to the end of the still kat which thegases enter, producing a fine intense spray of tar and pitch resultingfrom the distillation thereof in the still by atomizing or sprayingmeans which dips into the tar and pitch in the still whereby the tar israpidly distilled to pitch, withdrawing the pitch produced yfrom theopposite end of the still in a continuous manner, and continuouslywithdrawing gases and vapors resulting from the distillation from theend of the still at which the pitch is drawn off, and cooling the gasesand vapors to separate oils therefrom.

6. The method of distilling tar and producing distillate oils and pitchtherefrom, which comprises passing hot combustion gases at a temperatureof at least 500 C. intoa still, spraying them therein with a fineintense spray of partially distilled tar whereby the gases are rapidlycooled and pitch -is produced by further distillation of the tar,continuously withdrawing pitch from the still, bringing the resultinggases and vapors into indirect heat interchanging relation with the tarto be distilled, whereby the tar is heated and oils are simultaneouslycondensed from the gases, flashing the heated tar into a vapor box,thereby volatilizing low boiling oils, separately condensing such lowboiling oils and bringing the residue from this flashing operation intodirect contact with the hot 'gases in the still for further distillationthereof.

'7. The method of distilling tar and producing distillate oils and pitchtherefrom, which comprises burning a carbonaceous material, passing tarthru a pipe coil still in indirect contact with the resulting hotcombustion gases thereby partially cooling the'gases to a temperaturenot below 500 C., and heating and distilling the tar,.ilash ing theheated tar to remove low boiling. constituents therefrom and separatelycondensing such low boiling constituents, bringing the residue from thisashing operation into the partially cooled combustion gases in the formof a fine intense spray, whereby the residue from the flashing operationis distilled to pitch and the gases are rapidly cooled, withdrawing thepitch from the still and withdrawing the gases and vapors and condensingthem to separate oils therefrom.

8. The method of distilling tar and producing distillate oils and pitchtherefrom, which comprises bringing partially distilled tar into directcontact in the form of a fine intense spray with gases at a temperatureof at least 500 C. resulting from blending fresh hot combustion gaseswith a portion ofthe gases employed for prior distillation of the tar,thereby further distilling the partially distilled tar and producingpitch, withdrawing pitch from the still, withdrawing hot gases andvapors resulting from the distillation from the still, bringing tar tobe distilled into heat interchanging relation with these hot gases andvapors whereby they are cooled and oils are condensed therefrom and thetar isheated above the boiling vpoint of lower boiling constituentscontained therein, ashing the tar thereby -volatilizing low boilingconstituents, and conveying the residue of partially distilled tar tothe still for further distillation by direct contact with the hot gasestherein in the form of a ne intense spray and blending a portion of thegases coming from the still after separation of oils therefrom withfresh combustion gases thereby diluting the gases and cooling them to atemperature not below 500 C., and admitting the blended gases to thestill.

9. The method of distilling tar by direct contact with combustion gasesin combination with the operation of a coal distillation plant andproducing distillate oils and pitch therefrom, which comprises dilutingcombustion gases with fuel gases from the by-product recovery system ofthe coal distillation plant, thereby cooling them to a temperaturesuitable for distillation, spraying the resulting gases with a neintense spray of tar whereby the tar is rapidly distilled and pitch isproduced therefrom, and cooling the resulting gases and vapors toseparate oils therefrom.

10. The method of distilling ltar by direct contact with combustiongases in combination with the operation of a coal distillation plant andproducing distillate oils and pitch therefrom, which comprises dilutingcombustion gases with fuel gases from the by-product recovery system ofthe coal distillation plant thereby cooling them to a temperature notbelow 500 C., spraying the re-1 sulting gases with a fine intense sprayof tar whereby the tar is rapidly distilled andpitch is producedtherefrom, cooling the resulting gases and vapors to separate oilstherefrom, and blending the gases after separation of oils therefromwithfuel gases in the by-product recovery system before these fuel gasesenter the benzol extractor, and extracting therein light oil resultingfrom the tar distillation.

11. The method of distilling tar in combination with the operation of acoal distillation plant and producing distillate oils and pitchtherefrom, which comprises burning a portion 'of the fuel gas from thecoal distillation, diluting theresulting combustion gases with otherfuel gas to produce gaseshaving a temperature of at least ,500 C.,passing the gases at this high temperature into a still and sprayingthem with a fine intense spray of tar therein and distilling the tarthereby.

12. The method of distilling tar and producing distillate oils and pitchtherefrom, which comprises introducing hot combustion gases into a stillat a temperature in excess of 500 C., and filling the still with a fineintense spray of tar and pitch resulting from the distillation of saidtar, thereby exposing a large surface of the tar and pitch to thedistilling action of the hot gases whereby it is rapidly distilled andpitch is produced, while flushing the walls of the still with thematerial sprayed into the gases to prevent the formation of pitch orcoke deposits thereon.

13. The method of distilling tar, which comprises introducing into oneend of a still combustion gases at a temperature in excess of 500 C.,introducing tar into this end of the still and producing a ne intensespray of tar in this end of the still andv flushing the walls at thisend of the still with tar, and separately drawing oi from the other endof the still pitch and gases enriched in oil vapors resulting from thedistillation of the tar.

14. In combination with a still containing means for producing a i'lneintense spray of tar, a combustion chamber with means for burning acarbonaceous fuel therein, a pipe coil for heating tar located betweenthe means for burning the carbonaceous fuel and the still, a vapor boxconnected with said pipe coil, a separate condensing system for saidvapor box, and means for conveying residue from the vapor box to thestill.

15. In combination with a still containing means for producing a fineintense spray of tar, a combustion chamber with means for admitting airand a carbonaceous fuel thereto and for passing the combustion gasesinto the still, a heat interchanger and a vapor box with a condensingsystem connected thereto, means for conveying tar thru the heatinterchanger, means for passing gases and vapors from the still thru theheat interchanger in indirect contact with the tar, means for passingthe heated tar from the heat interchanger to the vapor box, and meansfor passing residue from the Vapor box into the still.

16. In combination with the by-product recovery system of a coaldistillation plant, a tar still with means therein for producing a neintense spray of tar, a combustion chamber, means for passing combustiongases therefrom into the still, and means for conveying fuel gases fromthe by-product recoverysystem and blending them with the combustiongases before they enter the still.

17. The method of distilling tar by direct contact with hot combustiongases at a temperature above that at which coking of tar may occur,which comprises passing the hot combustion gases into a still containinga body of tar, rapidly rotating a spray roll having its peripheral facesubstantially parallel to and dipping into the liquid surface of thebody of tar so as to form a spray of such intensity and in such anamount that the gases are almost instantly cooled toa temperature atwhich coking is avoided.

18. In combination with the by-product recovery system of a coaldistillation plant, a tar still with means for producing a iine intensespray of tar therein, a combustion chamber with means for conveyingcombustion gases therefrom into the tar still, means. for passing aportion of the fuel gases from the by-product recovery system into aburner operatedin connection with the combustion chamber to effectcombustion of the fuel gases therein, and means for blending otherfuel'gases from the by-product recovery system 150 1,97,sss

with the combustion gases before they enter the still.

19. In combination with a tar still with means for producing a neintense spray of tar therein, a combustion chamber and condensers, meansfor passing gases and vapors from the tar still to the condensers, meansfor blending a portion of the gases from the condensers with thecombustion gases and passing the blended gases into the tar still,vmeansfor stripping low boiling constituents from tar without substantiallydiluting vapors thus formed with inert gas, a separate condensing systemfor the recovery of these lw boiling constituents, and means for passingresidue froml the stripping operation into the tar still.

20. A method of distilling tar and producing distillate oils and pitchtherefrom, which comproduce a gas mixture having a temperature of atleast 500 C., introducing the gas mixture into a still containing abodyof the tar to be distilled, rapidly rotating a spray roll having itsperipheral face substantially parallel to and dipping into the liquidsurface of the body of tar so as to form a spray of such intensity andin such an amount that the tar is distilled to pitch and the gases arealmost instantly cooled to a temperature at which coking is avoided,withdrawing the resultant mixture of gases and vapors from the still andfurther cooling it to condense distillate oils. V

GREGORY EDWARD McCLosKEY.

